What Causes Physical Emotions

So I have random thoughts quite often. I like knowing useless knowledge but I also try to comprehend how our physical bodies connect with our spiritual selves. I wonder why it is that we feel emotion so strongly in our hearts. Why is it that emotional pain is so much more unbearable than physical pain? Why does your heart feel so much when you are sad, upset, heartbroken, etc.? I would rather be in total physical pain then being heartbroken. I wonder what our bodies go through to cause that pain. I understand that so much of our emotions are connected to our spiritual selves but there has to be a physical reaction also. Is it the nervous system? I don't know. If anyone has a good answer let me know. Is it just more evidence that we have a spiritual self. My friend Dan told me that your brain does not have pain receptors, therefore you can not feel pain in our brains. More proof that our mind and bodies are separate. Interesting don't you think?